Cycle News - Archive Issues - 1970's

What it's like to ride Marty's RC400 - - Honda's RC400 liB is amazingly clean and simple for a factory proto. There's 12 inches of air between tires and fenders. , . . Riding and techinical impressions 'Marty Sm-ith's ·championshi. p Honda RC400 liB . By,Jim Gianatsis Marty Smith's winning of the 1977 Mr. Pibb 500cc National Motocross Championship marked Honda's first major title won with the prototype RC Type II works bikes. Introduced' back in 32 April of 1976 . the 250cc machine. wh ich first appeared at H angtown tha t yea r, was com pletely redes igne d over the prototype CRs which had come before it. Ii b ore o n ly passing resemblance. to the outdated RC Type I models that the Honda team was using. 'When they were int rodu ced, the RC Type lIs were th e only motocross bikes designed completely, including the engine and . fram e, for use with long travel suspension. Until ' then . no ' other manufacturer , including Yamaha with its monoshock suspension , ' had designed other. components, like the engine, to ' work with long travel suspension. Honda of Japan shipped over the first RC Type lIs for the 250cc class at Hangtown in April of 1976. A few months later American Honda also received th e 125cc and ope n cla ss type lIs. Various bore and stroke . ratios were rumored to be available for the open class engine which gave it d isplacement sized anywhere from 380, 400 , 420 to 460cc. Presently though, the only engine size which Team Honda is using in the States for the open class is the 400cc version. This includes Marty's bike , which won the National Championship this year. When the new Type lIs were put in.to c~m peti tion l as~ year {hey m et . with mixed success. PIerre Karsmakers post ed th e new bik e's only wins , one a t the Southwick 250c c National and th e other at the St. Peters 500cc National. -Sorne people felt Marty Sm ith might have reta in ed hi s 125cc National Championship against Bob Hannah if ' th e RC 125 T ype II ha d be en ready at Hangtown , rather than two races before the end of the I25cc Championship Series. It is d oubtful though, because a\ many of th e ra ces the new T ype JIs wer e experiencing numerous problems . One of the biggest problems with the new Hondas was broken pistons. It wasn 't unusual to see the engin es torn d own after practice an d b etween motos at a National so t ha t the pistons could be inspected or repl aced . Pierre lost at least one race bec ause th e fu el taps on the tank, wh ich wer e located too close to the engine , broke off from the tank because th e engine either Vibra ted or flexed too much - in th e frame. Other problems included .th e Showa gas shocks that came on th e bikes, which didn't perform too well through a 45 -minute moto , " T he Honda 'e ngi neers in Japan couldn't understand wh y we were having such poor results with the new . • bikes ," explained Marty Smith's tuner Da ve Arnold. "They thoughtthey had . designed the ultimate motorcycle in the Type' II and figured we should .be winning all the time. At the end of the 1976 season the engineers got together with us for th e first time ever and listened to the problems we were having, along with what changes we thought sh ould be made to the bikes. " Ov er th e winter of 1976 /1977 the engi neers went to work on what was almost a co m p le te redesign of th e Type II . big b or e bik es. The 125cc m otocr osser seem e d pretty go od a lre a dy , an d since Ameri can Honda wou ldn't pu t a serio us efforr into 125 cc N atio nals fo r 1977 , it was m ore important to con centrat e on the 250 an d O pen class m ach ines. The result of a cras h program of red esign and test ing were th e ne w RC 25 0 Type IIBs introdu ced just in time for th is year's Supercross Series. O ver in Europe Br ad Lac key go t th e new RC 400 for t h e Gra nd Prixs, 'wh ile Am eric an H onda would ha ve to wa it, a li ttl e wh ile b efore th eir open cla ss ma chin ery a rrive d for the 500cc Na tion als. Right fro m th e beginni ng th e new T ype IIB s proved to be a n insta n t . success as Jim Pomeroy 'r a cked up a stri ng of 2 n d p la ce s b eh ind Bob Hannah in th e Supercross Series. Then when th e 250 cc Nati onals beg an , Sm ith and Pomeroy collected th e top two fin ish in g positions a t Hangtown and Southwi ck . The bikes were obvious ly good enough a n d only in consisrant riding b y S ith , > Pomeroy, a nd Tommy Croft kept the Hondas from winning any titl es. When the 500cc Nationals began though, it was a whole different story . Sm ith's speed and consistancy picked up to wh er e he was clearly able to put to good use th e reputation th e new Type IIBs had gai ned for reliability, handling a nd power. While Hannah suffered d esign and reliability problems with his works Yamaha , Smith and Croft pulled 1-2 punches at ' St. Peters , Unadilla and St. Petersburg ra ces to score t he top placings, and by th e time the 500cc Series was over Marty Sm ith was the new National Champion, Just m inutes after Marty had won th e 500 cc National Championship in SI. Pet ersburg. Florida , Honda team man ager T erry Mulligan gav e me permissio n to tak e Marty's cham pio nship -win ni ng RC 400 works bik e aroun d th e Sunsh in e Motocross ' Sp eed wa y track · for a few cautious laps. I was suprised it d id n' t take much b egg in g to convince T erry how interested Cycle N ews readers would be over riding im p ressions of Marty's bik e . " You' ll have to ask Dave, also ," said Terry. But that wasn't any probTem , since Dave Arnold was already out riding the bik e around the track after having just gotten it out of. the impound area : "Sure. Have fun ." said Dave " I guess we've got lots of extra fenders and tanks. But don't destroy it too bad. I' ve got to have it back together in time for the Trans-AMA." Although the bike appears similar to the Type II models except for the new rounded style gas tank, the RC 400 Type lIB is almost completely changed over last season. Things not readily apparent include the frame , which has slight geometry changes and has been beefed up in certain areas to cut down on cracking and flex. The new fuel tank has its fuel cocks positioned away from the engine to stop. the problems there. Last year's bikes used full width wheel hubs , which have now been replaced with magnesium conical hubs front and rear that are much lighter. The rear brake unit is full floating. Complete bike weight is under 210 pounds for the RC250 , and certainly right-on the FIM's 217 pound limit for the RC 400 open bike of Marty's. Honda is the only manufacturer to have d es igned a completely new engine since the advent of long travel ' rear su spen sio n , This has allowed Honda t o positi on the gearbox cou n tersha ft as far to the top and rear of the sand cast magnesium engine cases as possibl e. The resu lt is a lower cen ter of gravity despite th e additional ground clea ra nce needed for ' long travel. Also , th e countershaft sprocket is as close to the ' swingarm pivot as clearance a llows to provide the least amo u nt of tension ch a nge in th e drive c ha in d uri ng swi ngarm · tr ave l. Beca use of th is desi gn H ond a seems to have . no problem with th rown or brok en c ha ins, whil e othe r m anufa cturers are still fooling wit h th e p robl em after fou r yea rs. I'm still wai ting for someon e to get sm art and ac tua lly place th e swingarm pivot con centric wit h th e countershaft, You could n' t ' use a swin garm sha ft . but th e fr ame cou ld be reinforced in th e area of th e motor a nd swingarm mounts to handle th e a ddi tio na l stress. H ond a pi one e r ed ca se r e ed ind uction wit h its first RC s, but th e newer T ype lI s no w use cylinder reed induction . One reason offered for th is seem ing step back ward is that Suzuki b eat Honda to the punch . first .by putting it into production with their RM s. T his seems h ardly th e case though , be cause after riding the Type lIB I can attest to the fact I've never ridden a m or e powerful b ike with such a broad po werband. Additionally, I've ridden both Suzuki RM producti on a nd works b ikes , a nd while they exhibi t strong top -en d · power, their case reed induction engines are not as tractable over th eir entire RPM range as Yamaha , Husky, or the RC Type II works bikes. Another feature of the new engine is . that it is extremely easy to work on . The top end can be pulled with the cases still in the frame , a chore that can't usually be done with most cipen class bikes. Ignition timing can ' be

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